The present invention is concerned with a data carrier, the data face of which is furnished with parallel bars of different width and different spaces in the form of a bar code readable by optical data loggers (i.e., optical data detectors), with the data face, at least in part, being subdivided into rows or lines in which the bars are disposed in a direction vertical to the line axis. Equally, the invention is concerned with a method of reading a data carrier of the afore-described type.
One of the capabilities of coding information in machine-readable manner resides in that bars of different thickness be disposed at varying spaces in parallel to one another on a data carrier in accordance with a predetermined code. The bar code is broadly used with the European item number (EAN) for the clear cut identification of merchandise.
In that bar code printed, for example, on labels, the data face is provided with bars of the type whose length corresponds to an edge length of the rectangular data face. As the information is contained in the width of the bars and in the width of the spaces of the bars from one another, only one dimension of the data face is used for the data storage.
The afore-described data carriers involve the disadvantage that the information density is extremely low. In merchandise exhibiting sufficiently large faces for the provision of this data carrier, space requirements do not present a problem.
However, little space is available in high-quality microelectronical components of the type provided in integrated circuits and preferably containing individual identification characters. This applies, for example, to so-called EPROMS. Even the printed circuit board itself which in the course of the serial number allocation is furnished with bar codes in preparation for quality control, storage and quality warranty, avails of increasingly less space with rising information requirements.
Both jewel industry and jewel traders are attempting with the aid of ultra-high density coding which is difficult to read, to accommodate the information in an axis. Here, too, there is a need for accommodating a multiplicity of data in a relatively small face. Medical technology is encountering the problem of that, increasingly, an automatically readable description of medical drugs is being required, in respect of which the previously used data carriers furnished with bar codes are unsuitable in view of their substantial space requirements as medical drugs as such are always accommodated in small-sized packs.
Similarly, industry, increasingly, is required to provide tools or small-sized parts for employment in the most various fields of end-use application, with a corresponding code, permitting an automatic identification of substantial information content in minimum space.
The automobile industry has already been using tickets accommodating the whole of the information of up to 40 symbols in approximately six lines. However, no attention has been given to consistent space savings.
To solve the afore-described problems, Code 49 has been developed, which is a bar code disposed line by line in the data face. The lines are disposed one below the other, completely filling the rectangular data face. This bar code disposed line by line requires the lines to be read by the logger in the proper order of sequence. In case of manual systems, the operator will have to cause the system to scan the data carrier line by line.
However, when using an automatic reader in which the laser beam guided across the data carrier crisscrosses along a predetermined path such that the data carrier can be read in any desired position, the lines are not scanned in their proper order, with one or several lines also being read in the diagonal direction, resulting, in decoding, in a data mix having nothing in common with the actual information content of the data carrier.
To overcome this problem, according to Code 49, the symbols are combined to form words and, according to a predetermined code, are provided with a parity to thereby enable, in decoding, a line association by way of the parity pattern. In addition, at least one control symbol is needed containing, among others, the number of lines.
This type of arrangement of the bar code, concerning the evaluation thereof, is extremely complex, not offering the reliable readability required in the art. In diagonal reading, a parity combination can be logged portending a predetermined line number, in which case the information as read will not correspond to the information content of the corresponding line so that errors are likely to occur when employing conventional readers.